Conventionally, there is known the technology in which a moving speed detection unit is provided in a radio system, such as a mobile phone, and a moving state of the radio system (or a moving state of the person who uses the radio system) is determined based on a detection result from the moving speed detection unit, and, in response to the detected moving state, automatic switching of the radio system to the handsfree talk mode, regulation of the call origination of the radio system concerned, or notification of a warning message or the like to the person concerned is carried out. For example, see Japanese Laid-Open Patent Application No. 10-190557.
Also known is the technology in which, in order to regulate communication of a portable terminal in the passenger compartment, a sensor unit for detecting the open/close state of a vehicle door is provided, and electromagnetic waves which regulate communication of the portable terminal are transmitted when the door open/close state is detected. For example, see Japanese Laid-Open Patent Application No. 2003-174674.
In recent years, in order to secure safe use of a portable terminal, such as a mobile phone, in the passenger compartment, the use of a handsfree device in the passenger compartment is proposed.
With the use of the handsfree device, connection between the handsfree device and the portable terminal is established at the time of use (typically, in the talking mode) of the portable terminal, and the transmission of a voice signal between the handsfree device and the portable terminal is possible. This eliminates the necessity that the user holds the portable terminal by hand.
However, once the connection is established between the handsfree device and the portable terminal, there has been no mechanism which restricts in any way the mode switching between the handsfree mode in which the handsfree device is used and the portable terminal stand-alone mode in which the portable terminal is used in isolation. For this reason, there is a problem in which the security becomes inadequate in making compatible the convenience of the portable terminal and the safety of the vehicle running.